Abstract Seven hypotheses, including the ‘Resource Concentration Hypothesis’ and ‘Enemies Hypothesis’, have been put forward to explain why fewer specialist insects are found on host plants growing in diverse backgrounds than similar bare soil. All seven hypotheses discussed discounted, primarily because no one has used any of them produce a general theory plant selection, they still remain as hypotheses. However, we developed based detailed observations insect behaviour. Our is fact that...

Using mimics of real plants, we found that female cabbage root flies, Delia radicum (L.), detected plants within host patches at least partly on the basis leaf colour and area, with pattern playing an insignificant role in case multi‐leaved plants. Composition background, whether bare soil or green grass, did not affect ability to distinguish between different colour. The contribution visual stimuli eliciting landings individual a patch decreased as distance was increased. RÉSUMÉ Repérage...

In experiments in which spectrophotometric reflectance patterns of real leaves were mimicked with mixtures artists' pigments, leaf color was shown to be a character used by cabbage root flies, before landing on leaves, discriminate among the host plant cultivars radish, green cabbage, and red cabbage. It may possible take advantage factors that affect color, such as epicuticular bloom, pubescence, masking chlorophyll other decrease attraction certain pest insects plants.

Abstract Companion plants grown as ‘trap crops’ or ‘intercrops’ can be used to reduce insect infestations in field crops. The ways which such reductions are achieved being described currently using either a chemical approach, based on the ‘push‐pull strategy’, biological ‘appropriate/inappropriate landing theory’. approach suggests that numbers reduced by chemicals from intercrop ‘repelling’ insects main crop, and trap‐crop ‘attracting’ away crop. This is assumptions (1) release detectable...

Abstract Brassica and Allium host‐plants were each surrounded by four non‐host plants to determine how background affected host‐plant finding the cabbage root fly ( Delia radicum L.) onion [ antiqua (Meig.)] (Diptera: Anthomyiidae), respectively. The 24 tested in field‐cage experiments included garden ‘bedding’ plants, weeds, aromatic companion one vegetable plant. Of 20 that disrupted fly, fewest eggs (18% of check total) laid on host weed Chenopodium album L., most (64% those Fumaria...

Mild‐strain cross protection was used in field trials at Wellesbourne and Jersey attempts to protect courgette plants against severe strains of zucchini yellow mosaic virus. Test were sap inoculated with the mild strain then challenged by an aphid‐transmitted after different periods. Approximately 14 days incubation required following mild‐strain inoculation provide subsequent infection strains. No occurred if introduced 2 (48 h) intermediate severe‐strain challenge 7–8 days. Some breakdown...

SUMMARY A program for simulating the patterns of egg‐laying by populations cabbage root fly was used to model effects global warming on future attacks. An increase 3°C in mean daily temperature would cause become active about a month earlier year than at present. Under such conditions, emergence flies from overwintering population be less synchronised, as completion diapause and post‐diapause development occur same time different individuals within population. However, there continue only...

Abstract Laboratory experiments showed that 4°C, rather than 6°C as used previously by most authors, was a suitable base temperature for calculating the number of day-degrees C required to predict time emergence in spring Delia radicum (L.); 1 February an appropriate date start accumulation, more 50% pupae had completed diapause this and were therefore able proceed with their development.The fly estimated accurately from accumulated 6 cm deep soil, average depth overwintering puparia, air...

Domesticated lettuce varieties encompass much morphological variation across a range of crop type groups, with large collections cultivars and landrace accessions maintained in genebanks. Additional not captured during domestication, present ancestral wild relatives, represents potentially rich source alleles that can deliver to sustainable production. However, these are difficult costly screen for many agronomically important traits. In this paper, we describe the generation diversity...

Vegetables are a key component of healthy diet, but they also exposed to relatively high amount pesticide usage in conventional growing systems. A generally agreed aim Integrated Pest Management (IPM) is reduce reliance on ‘chemical control’ using synthetic pesticides, usually placed at the top IPM pyramid. This review focuses approaches bottom pyramid relation pest insects root, bulb and leafy vegetable crops northern Europe. These concern establishment crop before any additional treatments...

ABSTRACT. Once pupal diapause had been terminated, over‐wintering cabbage root fly ( Delia radicum (L.)) pupae from Wellesbourne required a further 14 days at 20°C for most of the flies to emerge. There were considerable variations in rates emergence thirteen populations collected between latitudes 50° 42′ and 54° 59′ England Wales. These could be grouped into early‐, intermediate‐ late‐emerging types. In early‐emerging type, emerged within whereas type was protracted completed only after...

Low temperature was shown to be the major factor regulating diapause development of cabbage root fly. Diapausing pupae had subjected temperatures from 0°—6° for 22 weeks all individuals in population complete development. Once this complete, required a further 14 days at 20° most flies emerge. Flies that emerged within 20°, criterion completion, were classed as early‐emerging. The percentage early‐emerging gradually increased period low extended 12 weeks. In range 0° 10°, parallel linear...

In the UK, severe infestations by Plutella xylostella occur sporadically and are due mainly to immigration of moths. The aim this study was develop a more detailed understanding phenology P. in UK investigate methods monitoring moth activity, with providing warnings growers. monitored using pheromone traps, counting immature stages on plants, accessing citizen science data (records sightings moths) from websites Twitter. likely origin migrant moths investigated analysing historical weather...

Abstract The angle of inclination the surface on which flies prefer to land in vegetable crops was studied field plots and field‐cages using one‐sided sticky traps aligned one plane but orientated eight directions. four Delia species studied, D. antiqua, floralis, platura radicum , preferred horizontal surfaces, indicating that they are likely be trapped largest numbers with a trapping surface, such as water traps. This trend even more pronounced Syrphidae. In contrast, greatest carrot fly,...

Abstract Six‐hundred individual female cabbage root flies ( Delia radicum L.) (Diptera: Anthomyiidae) were each observed for 20 min under laboratory conditions to record how they behaved after landing on a host or non‐host plant. Fly movements recorded plants [cabbage – Brassica oleracea var. capitata (Cruciferae)] and [clover Trifolium subterraneum L. (Papilionaceae)] surrounded by bare soil clover. The most frequently behaviours made the (1) hops/spiral flights (2) walks/runs. In...

Abstract Laboratory experiments at 16°–30°C showed that the cabbage root fly can only be induced into aestivation during early part of pupal stage. The relationship between percentage pupae entering ( y ) and average daily temperature T was same under both constant alternating temperatures. a particular given by = 13 — 255. An additional 13% entered for each degree rise 20° 27° C. There no period arrested development following induction aestivation. Aestivating started to develop flies as...

Abstract BACKGROUND: The aim of this study was to assess white mustard ( Sinapis alba L.) as a trap crop for diamondback moth [ Plutella xylostella (L.)] on cauliflower Brassica oleracea (L.) var. Lateman]. Moth behaviour these plants and the importance plant age size in maintaining pest preference were also investigated. RESULTS: Three times many eggs laid that unprotected than protected by mustard. Moths remained longer result doubling mean duration information‐providing behaviours. Plant...

Abstract Aphid genomic resources enable the study of complex life history traits and provide information on vector biology, host adaption speciation. The currant–lettuce aphid ( Nasonovia ribisnigri (Hemiptera: Aphididae ) (Mosley)) is a cosmopolitan pest outdoor lettuce Lactuca sativa (Asterales: Asteraceae) (Linnaeus)). Until recently, use resistant cultivars was an effective method for managing N . A cultivar containing single gene (Nr‐locus), introduced in 1980s, conferred complete...

Abstract Agricultural improvements that reduce conventional pesticide use and support environmental aims are a priority. Current approaches develop promising alternative products but meet significant challenges in bringing them to market. This article reports findings of an Association Applied Biologists event at which delegates from relevant industry sectors discussed the establishment effective integrated pest management innovation system linking multiple stakeholders. Interrelated...

The various diapause and post‐diapause stages entered by cabbage root fly pupae during the overwintering period are shown schematically. Although induction started in mid‐Aug., early‐pupating insects did not develop further but were maintained warm autumn temperatures. Therefore, development was simultaneous all Wellesbourne pupae, whether of second or third generation origin. Diapause only mid‐Oct., when mean soil temperatures fell below 10°. In field, 90% population had completed 5 March...

It is shown that sulpholipid the predominant acetone-insoluble lipid of grass, sphagnum moss, Selaginella, and some blue-green, green brown algae. This separable into three entities by paper chromatography. Phospholipid predominates over in red algae, fungi fluffy pericarp broad bean. The these plant tissues gives a single spot on chromatogram A relationship between sulpholipids photosynthesis suggested.